Vacuum tube



Nov. 12, 1935- l. E. MOUROMTSEFF VACUUM TUBE Original Filed March 6,1929 .RW. Y m m 2 m V0 T WW ,V.A E m 9 6 z 2. MV a0 M W w /2 W 0 w f f,2 I z T n M 6 h x 5 a J V A M 2 7 w Z W 9 2 WITNESSES:

Patented Nov. 12, 1935 UNITED STATES PATENT OFFICE VACUUM TUBEPennsylvania Continuation of application Serial No. 344,772, March 6,1929. This application April 14, 1933,

Serial No. 666,162

. 4 Claims. (Cl. 250-275) This application is a continuation of mycopending application Serial No. 344,772, filed March 6, 1929, nowPatent 1,944,190, issued Jan. 23, 1934, and the invention hereindescribed is 5 disclosed in Fig. '7 of this copending application.

My invention relates to electron discharge tubes having a controlelectrode and particularly to electron discharge tubes designed forgenerating large amounts of power or for generating very high frequencycurrents.

It has hitherto been proposed to make the control electrode acylindrical body with longitudinally extending grooves therein, and toplace the filaments forming the cathode structure of the tube at thebottom of the grooves. I have found, however, that when the grid ispositive this large mass of material substantially enclosing thefilament absorbs a large part of the electrons emitted from thefilament, and hence cuts down the plate 20 current to the anode. I havefurther found that the enclosing grid structure of this type of tubenarrows the beam of electrons-directed towards the anode with the resultthat they are concentrated on a small portion of the area of theanode I25 and cause overheating and puncture of the tube at these particularareas. Furthermore, in order to have an appreciable value ofamplification, the filaments must be located very close to the bottom ofthese grooves with the result that any sagging of the filament is likelyto cause the filament to touch the surrounding grid structure and shortcircuit thereto.

I avoid these disadvantages of the prior art construction just referredto by having a built up central grid structure with radial projectionstherefrom having enlarged ends and by locating the filaments so thatthey are adjacent only to these enlarged ends and not to the remainingsections of the grid structure.

Other features and advantages of my invention will appear from thefollowing description taken in conjunction with the accompanying drawingin which:

Figure 1 is a view in longitudinal section of a power tube constructedin accordance with my invention; and,

Fig. 2 is a view in lateral section taken on the line II-II of Fig. 1with the details of the upper end portion of the tube left out for thesake of clearness.

Referring to the drawing the apparatus comprises a vacuum tightcontainer formed by an outer metal tube In which acts as the anode andwhich is closed at the upper end by a metal piece in g i th u The lowerend of the tube is closed by means of a glass member I2 which is sealedto it by means of a metallic reentrant portion I3 sealed to a reentrantportion of the glass member I2 at the seal I4.

The metallic reentrant portion I3 forms the 5 structural part of thegrid of the power tube and is in the form'of a metal tube I5 closed atthe upper end by means of a metal piece integral with it. A pipe I 6 ispositioned within and spaced from the tube I5. By means of thisstructure the 10 grid may be cooled by forcing water or some othercooling fluid into the reentrant portion I3 between the tube I5 and thepipe I6 and out through the pipe I6.

Surrounding the pipe I5 is a tube I8 to which a plurality of U-shapedmembers I9 of sheet material are welded or otherwise suitably attached.These members are assembled in contact with each other to form ribsprojecting laterally from the tube I8. Each rib supports a rod welded 20or otherwise suitably attached thereto in such position that it isparallel and adjacent to a filament 2i, whereby a very effective gridcontrol is obtained. The control effect is exerted by the rods 26 whilethe ribs formed by members I9 conduct the heat away from the rods.

The upper ends of the filament 2| are supported and electricallyconnected by means of rods 22 secured to a metal ring 23. The supportingstructure for the ring 23 comprises a rod 24 of insulating material suchas quartz that is clamped in a split supporting member 25 which iswelded or otherwise attached in any suitable manner to the upper end ofthe reentrant portion I3. The ring 23 is attached to the upper end r ofthe rod 24 by means of another split supporting member 26 which isattached to the ring 23 and clamped to the rod 24.

The lower ends of the filaments 2i are attached to rods 21, supported bymeans of rings 28 which are bolted to terminal rods seated in thereentrant portions 29 of the glass member I2. Several filaments aresupported by each of these rings 28.

It will thus be noted that I have provided an electron discharge devicewith an exterior anode and a central control electrode or grid structureand a cathode structure comprising a plurality of filaments intermediatethe central electrode structure and the exterior anode. The filamentstructure is placed adjacent to the outer enlarged ends of the controlelectrode and hence the grid structure will not absorb a large massofelectrons when the grid is positive, as would be the case if thefilaments were located well within the U-shaped members H). The enlargedends 20 of the radial projecting portion of the grid will thus controlthe anode current without producing a detrimental robbing effectthereon. The electrons passing from the filament 2| to the anode ID'will have a large area upon which to strike the anode I0 and will notbe restricted to a small area, as they would be if they were located inthe bottom of the trough formed by the U-shaped members 19.

Various modifications may be made in my invention without departing fromthe spirit and scope thereof, and I desire-therefore, that only suchlimitations shall be placed thereon as are shown by the prior art andset forth in the appended claims.

I claim as my invention:

1. An electron discharge device comprising a vacuum tight container, ananode constituting a portion of the outer wall thereof, a controlelectrode-within .said container vand having projections extendingtowards .said anode and a cathode structure intermediate saidcontrolelectrode and said anode, and closer to the latter than are theends of said projections.

2. An electron discharge device comprising a vacuum tight container,.ananode constituting a portionof the outer wall thereof, a controlelectrode structure within said container, means for directing a coolingmedium to a portion of said control electrode structure, radialprojecting portions of said control electrode structure extending towardsaid anode, and a cathode structure intermediate said control electrodestructure and said anode, and spaced closer to the outer ends of saidradial projecting portions than to the remainder of said controlelectrode structure.

3. An electron discharge device comprising a vacuum tight container, ananode constituting a portion of the outer wall thereof, a controlelectrode structure within the central portion of said containenradialprojecting portions of said control electrode structure extending towardsaid anode, the ,outer ,ends of said portions being greatly enlargedover the intermediate section of said radial projecting portions and acathode structure intermediate said control electrode structure and saidanode, and spaced closer to the outer ,ends of said radial projectingportions than to the remainder of the control electrode structure.

,4. An electrondischarge device comprising a control electrode .havingradial projecting portions, a cathode structure comprising filaments andan anode surrounding said control electrode 25 projecting portions.

ILIA E. MOUROMTSEFF.

